Devices for stacking generally planar articles of material, such as sheets of corrugated material, are well known. One example of a commercially available device is the AGS2000 Rotary Die Cut Stacker made by the assignee of the present invention, A.G. Stacker, Inc., Weyers Cave, Va. Further examples of such devices are disclosed in U.S. Pat. No. 3,321,202 to Geo. M. Martin and U.S. Pat. No. 3,419,266 to Geo. M. Martin, each of which is expressly incorporated herein by reference in its entirety.
As shown in FIGS. 1 and 2, a conventional stacking apparatus 100 generally comprises a layboy section 102 which receives sheets, such as corrugated blanks produced by a rotary die cut machine 103, and discharges the sheets onto a transfer conveyor 104. The transfer conveyor 104 receives the sheets and transports them to a main conveyor 106. The main conveyor 106 has an intake end 108 and a discharge end 110, and the transfer conveyor has an intake end 112 and a discharge end 114. At the main conveyor intake end 108, the main conveyor 106 is mounted to a base 116 at a pivot point 118 so that the main conveyor 106 may be pivoted to raise its discharge end 110. At the discharge end 110 of the main conveyor 106, an accumulator section 120 receives discharged sheets.
The transfer conveyor 104 includes a plurality of parallel belts 122 that extend in a longitudinal or downstream direction from the layboy section 102 to the main conveyor 106. In FIG. 1, these belts are parallel, and the ends of the belts at the intake end 112 and at the discharge end 114 are equally spaced in a transverse direction (transverse to the longitudinal direction). This configuration is adequate for transporting a single stream of sheets. However, it is known to configure a rotary die cut machine to produce multiple (two, three, four or more) streams of sheets simultaneously. It is sometimes desirable to increase the lateral separation between the streams of sheets so that, for example, the stacks formed by the main conveyor section are laterally separated.
It is therefore known to provide a transfer conveyor with belts having ends that can be manually repositioned. For example, if the transfer conveyor has a longitudinal centerline and eight belts, a first set of four belts on one side of the longitudinal centerline and a second set of four belts on the other side of the longitudinal centerline, the downstream ends of each set of belts may be shifted laterally outwardly away from the longitudinal centerline. Two streams of sheets that arrive at the intake end of the conveyor separated by a first distance may thus leave the discharge end of the transfer conveyor separated by a second, greater, distance.
Manually repositioning the ends of the belts of the transfer conveyor can be time consuming, and it may sometimes be difficult to ensure that a given spacing of the belt ends can be repeated accurately each time a particular product is processed. It would therefore be desirable to provide a transfer conveyor having belts the ends of which can be positioned consistently and automatically.